This invention relates to novel composite and conjugate filaments adapted highly and exclusively for use in in-water submerged state services and providing superior and improved dynamic impact strength, water-resisting and anti-friction performancies.
As is well known, polyamide filaments represent superior tensile strength, knot strength, modulus of elasticity and antifriction performance and highly suitable for use in in-water submerged services, especially as fishing lines, fishing nets and marine ropes. Although the polyamide filaments show still superior antifriction performance in contact with water, because they absorb a certain amount of water and become rather soft and pliable, while they are subjected to elongation in length and substantial reduction in strength.
When a polyamide fishing line is used for fishing purposes, and a large fish bites, a substantial tensile impact will be applied to the fishing line which is however rather poor to the fish-on shocks in the water-submerged state. Similar and even accentuated and repeated impacts may be applied to a moorage rope composed of a large number of polyamide fibers which are rather weak in tensile strength when subjected to continued contact with water. Therefore, much is desired to improve the tensile shock impact resistance of these lines and ropes.
It was already proposed by Kureha Kagaku Kogyo Kabushiki Kaisha, Tokyo, Japan, the assignee company of the present application, in Japanese Patent Publication No. Sho-44-5359, to provide fisherman's lines and ropes made of polyvinylidene fluoride. These fishing lines have been manufactured and sold by the said assignee company under the trade name of "Seager" and "Max" and acquired favorable criticism among those skilled in the art. These PVDF-filaments represent substantially higher tensile strength as well as knot strength than polyamide filaments and it has been found that these superior values will be subjected to almost no reduction even in the in-water service conditions. Therefore, in the fishing and the like in-water services, the PVDF-filament shows substantially superior performance in this respect over the corresponding denier polyamide filament, while the former represents rather lesser elongation rate in the water. It should also be stressed that the PVDF-filament has several times higher impact strength than the corresponding polyamide filament.
On the other hand, it has been observed that the antifriction performance of PVDF-filaments is slightly lesser than that of polyamide one, thus turbo-flies being generated in contact with a rocky edge or the like and the former being subject to breakage under certain conditions.